464 QUEENSLAND AGRICULTURAL JOURNAL. [1 Dec., 1898, 
succulent parenchymatous tissue that is immediately continuous with the thin 
floor of the chamber, and that forms in proceeding downwards the so-called 
placental column and placenta of the ovary ; especially (1) that part of this 
that is beneath the abovementioned three depressions at the base of the style, 
and (2) the almost open central line (the so-called placental axis of botanists) 
that 1s continuous with the narrow channel enclosed by the three conjoined 
styles that form the pistil. a 
On dividing longitudinally a number of fruitlets so as to expose to view 
different stages in the development of the disease, one will remark that tbe 
“‘core-rot’’ invariably commences as asmall spot (often a mere speck) not only 
immediately beneath the chamber, so often alluded to, but precisely at the sites 
mentioned as being especially vulnerable ; and that as the malady progresses 
it proceeds downwards from these sites into the placental column and placenta 
(to which the seeds are attached), along the central or placental axis, or along 
narrow tracts of tissue that terminate outwardly in one or more of the afore- 
mentioned three depressions at the base of the style. (Plate LXX., Figs. 2, 
3, 4.) : 
This is explicable when one appreciates the fact that the spores of the 
Monilia fungus—since they are so often naturally present in the fruitlet cavity, 
as has been before stated, and since, as has already been observed, they 
germinate readily in fresh pineapple juice—can gain access to the tissue at 
these spots where the Tarsonemus Mite has been prosecuting its feeding habit. 
Once established at these seats of injury, the further development of the fungus 
and the chemical changes that are a consequence of its growth proceed down- 
wards into the tissue along the above-mentioned tracts—as lines of least 
resistance—in especially suitable tissue, until eventually almost the entire 
ovarian portion of the fruitlet becomes affected, and the fungus itself develops 
reproductive organs in the loculi or seed cavities, filling these with hyphe and 
myriads of, for the most part, free spores. Chemical change in the fruit- 
tissue manifests itself, amongst other ways, especially, by the appearance of 
(1) a dark-brown discolouration that attends the growth of the fungus from 
the very outset; and by (2) a retardation in the maturation of the fruitlet as 
a whole (hence the green patches occurring externally on affected pineapples) ; 
those special transformations in the constituents of unripe fruit that constitute 
the ripening process being apparently temporarily inhibited. ‘ 
1t would, moreover, appear that the latter special chemical transformations 
and the changes constituting the disease are directly antagonistic, and that when, 
as during the summer months, the former are intensified—as shown in the reduced 
period occupied in ripening—the latter cannot proceed. And this may be the 
explanation of the fact that little core-rot is remarked during the season of the 
year attended to. In winter the reverse condition obtains, the ripening 
process is protracted, and hence the prevalence of ‘“ core-rot.” 
The disease described on page 459 as affecting the fruit of the Smooth- 
leaved Pineapple presents characteristic differences, as has been already 
remarked, as compared with that occurring in the Prickly Queen variety. It does 
not commence exactly in the same position in the fruitlet; it involves the decay 
of another portion of it, and it is associated with a distinct fungus. This is a 
species of Penicillium otherwise found occurring almost always upon the dead 
and dried-up stamens and pistil. In so much, however, as it develops a prolific 
growth, it may early mask the external manifestation of the MJonilia. But 
nevertheless accordingly, although Mites—both Zursonemus and Tyroglyphus— 
have been found associated with it at the time of its very commencement, it 
can only be presumed that the explanation above given for the “core disease” 
in the Prickly Queen variety will apply also to it. However, the two diseases, 
if not identical, are certainly closely analogous. 
ACCIDENTAL CAUSES. 
Tn addition to the Tarsonemus Mite that has been shown to perform such 
an important role in connection with the origin of the disease, there are other 
acari also that occur with more or less constancy within the cavities affected 
. 
